A unknot is pretty much a circle or a 2-sphere, so is a closed string, maybe a bit more irregular but approximatly the same. Of course more is needed to identify the closed string as an unknot than the shape. I assume that it is not so, yet I have no reason to deny it. I hope you may give me a reason. Knots can also be added simply connecting the two knots. Is such a addition also possible with closed strings, if they are in fact unknots? Can, if it is a unknot, the closed string me knoted further?